Well, they would ask why he's always wearing his mask/visor. They're curious on what he would look like without it, but they won't go to the extent to try and remove the mask if Master is dead serious on saying not to do it. Teny may be a tease sometimes, but she would never cross any boundaries and be respectful. Neither both of them don't want to make Master uncomfortable or brake his trust, so they'll let him and his mask alone.
Though if they'll be a time when Master trust them enough to remove his mask and show his face, they'll understand why he was very skeptical to remove it. Also, they have seen way worse horrors imaginable so it's doesn't phase them. Or they would be amazed if he has some cool features

Different as in him being nice to them? Well both of them would be amazed there's dark matters that relatively are not as hostile than expected. They'll understand why he hates his race, but also it gives them hope that if there's one nice DM, then there would be more of them somewhere
And yeah, Som really can relate to the whole overprotectiveness. So does Teny with Gooey, but she trust Kirby into taking care of him so she's more lax than Som